add 92

Author: cch123

S0092-reverse-linked-list-ii/Cargo.lock

@@ -0,0 +1,8 @@
+[package]
+name = "S0092-reverse-linked-list-ii"
+version = "0.1.0"
+authors = ["xargin <cao1988228@163.com>"]
+edition = "2018"
+
+[dependencies]
+leetcode_prelude="^0.1"

S0092-reverse-linked-list-ii/Cargo.toml

@@ -0,0 +1,51 @@
+use leetcode_prelude::*;
+fn main() {
+    let l = linkedlist![1,2,3,4,5];
+    let x = Solution::reverse_between(l, 2,4);
+    println!("{:?}", x);
+}
+
+// 本质上还是遍历了 1.x 遍
+// 好像没有办法像其它语言那样记录多个指针？
+struct Solution;
+impl Solution {
+    pub fn reverse_between(mut head: Option<Box<ListNode>>, m: i32, n: i32) -> Option<Box<ListNode>> {
+        if head.is_none() {
+            return head
+        }
+        let mut cur  = &mut head;
+        let mut cur_idx = 1;
+        while cur_idx != m {
+            cur_idx += 1;
+            cur = &mut cur.as_mut().unwrap().next;
+        }
+
+        let mut prev = None;
+        while cur_idx <= n {
+            cur_idx += 1;
+            // swap(prev, next)
+            // prev == next
+            std::mem::swap(&mut cur.as_mut().unwrap().next, &mut prev);
+            // swap(prev, cur
+            std::mem::swap(&mut prev, &mut cur);
+        }
+
+        let tail = std::mem::replace(cur, None);
+
+        // connect mid and tail
+        let mut mid_cur = &mut prev;
+        while mid_cur.is_some() {
+            mid_cur = &mut mid_cur.as_mut().unwrap().next;
+        }
+        std::mem::replace(mid_cur, tail);
+
+        // connect head and mid
+        let mut head_cur = &mut head;
+        while head_cur.is_some() {
+            head_cur = &mut head_cur.as_mut().unwrap().next;
+        }
+        std::mem::replace(head_cur, prev);
+
+        head
+    }
+}